A lamp device using an LED element having low power consumption and a long life has been generally proposed as a light source usable in place of, for example, a straight-tube type or self-ballasted fluorescent lamp. As disclosed in, for example, Japanese Laid-Open Patent Publication No. 2009-158111, such a lamp device has a DC power source portion and a lighting circuit for lighting an LED lamp including the LED element with use of power supplied from the DC power source portion.
For an LED lamp system, in terms of convenience and saving-energy, it is not preferable that the lighting circuit operates with the LED lamp not attached to the lighting circuit, so it is preferable to be able to detect attachment of the LED lamp.
However, although, in the case of, for example, a lamp device using a fluorescent lamp, attachment of the fluorescent lamp can be detected based on voltage division with use of a resistance value of a filament, such as an attachment detection with use of a resistance value is impossible in the case of an LED lamp having no filament. Accordingly, in an LED lamp system using an LED lamp, it has been demanded that attachment of the LED lamp can be detected.
In view of the above problem, the present invention has been made and aims to provide a power source unit for LED lamps which can reliably detect attachment of an LED lamp, and an LED lamp system including the power source unit.